How are you running the audio? For example i have my 360 hooked up to a stereo receiver via HDMI cable. So the TV gets both sound and picture. But my Turtle Beach require their own audio source, so for those i use the audio dongle/adapter that comes with the 360 to run the red/white cables out so the headset also has audio. If you have hook ups for red/white cables why not just use them to begin with rather than trying to down convert optical to analog?